PURPOSE: To further improve the efficiency of cooling and heating within a range of limited capacity of a cooler heater mounted on an automobile.

CONSTITUTION: An air bag 1 for regulating temperature in an automobile is formed such that a bag made of a synthetic resin sheet to partially occupy the space of the passenger room or the cargo room of a vehicle when air is pressed therein for inflation is partially fixed in a folded state to the inner ceiling of a car and the opening part 1a of the bag is coupled to an air feed pipe 4. By inflating the air bag 1 when no cargo is loaded or an amount of loaded cargo is low, a space not needing cooling and heating is cut off and the efficiency of cooling and heating is improved.